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Today marked the start of a new era in astronomy as NASA’s Wide-field Infrared Survey Explorer (WISE) spacecraft took flight and was successfully placed into its polar orbit by the venerable Delta II launch vehicle.

At 06:09:33 Pacific Standard Time (14:09:33 UTC), Space Launch Complex 2-West at Vandenberg Air Force Base lit up with the fire and thunder of WISE’s Delta 7320-10C Med-Lite vehicle. With only two stages and three strap-on booster motors, the 7320 has the least total impulse of any of the Delta II vehicles; nevertheless it had plenty of oomph for WISE, a lightweight craft that weighed less than three-quarters of a ton—1,457 pounds—at liftoff.

This marked the 92nd consecutive success for Delta II, an exemplary record dating back over a dozen years. In addition, the United Launch Alliance has now tallied 37 consecutive successes—one hundred percent—in its 36 months of existence. (Delta II accounts for 21 of them.)

The Wide-field Infrared Survey Explorer will survey the entire celestial sphere at least once during its nine-month mission. It is a follow-on to IRAS and COBE, two infrared surveyors that each launched aboard Delta vehicles—Delta 166 (25-Jan-83) and Delta 189 (18-Nov-89), respectively. The sensor package aboard WISE has a sensitivity at least a thousand times greater than those of its predecessors, made possible by a cryostatic system that uses solid hydrogen to keep cool. The hydrogen, weighing 35 pounds at liftoff, will gradually heat and boil away into the near-vacuum of space; hence the short mission duration.

WISE is part of NASA’s Explorer program, a series of scientific spacecraft that is older than the agency itself. More than three dozen Explorer missions have been lofted by Delta rockets, several of them still active—among them XTE, ACE, WMAP, and Swift. However with the Delta II production line shut down, and only five launch vehicles left unassigned, it is very possible that today’s launch will be the last teaming of Explorer and Delta.

The next launch of a Delta II rocket, carrying NASA’s WISE infrared surveyor, has been postponed by three days. During final checkout on 9 December, one of the vehicle’s main-stage vernier engines was found to have excessive resistance to movement. A suspect component will be swapped out. The twin vernier engines flank the Delta II main engine and provide the primary roll control (as well as some pitch and yaw control) during the first stage of flight.

The next Delta II launch will be Worldview-2, a commercial Earth-imaging satellite owned by DigitalGlobe of Longmont, Colorado. The launch from SLC-2W at Vandenberg is set for 8 October, a two-day delay caused by postponements in the launch of Delta 344. Worldview-2’s predecessors, QuickBird-2 and Worldview-1, each launched aboard Delta II vehicles.

The second launch of the year by Delta II for the Department of Defense’s Missile Defense Agency has completed successfully.

Liftoff from Cape Canaveral’s SLC-17B occurred on Friday, 25 September, at an official range time of 08:20:00.223 EDT. The 65° flight azimuth took the Delta II vehicle over Europe for the first time since Mars Odyssey in 2001 (Delta 284).

This mission deployed a pair of remote sensing satellites that will demonstrate the space-based component of “a layered Ballistic Missile Defense System (BMDS) designed for the overall mission of detection, tracking, and interception of ballistic missiles.” Both satellites were deployed less than an hour after liftoff while in range of the Diego Garcia tracking station in the Indian Ocean, into circular orbits about 729 nautical miles in altitude.

Launch was scrubbed on two previous days for weather conditions. The delay has impacted on the next Delta II flight, Worldview-2, which was previously slated for 6 October from Vandenberg AFB but has not yet been rescheduled.

On Monday, 17 August 2009, the last U.S. Air Force Delta II was launched from Cape Canaveral Air Force Station, placing a GPS satellite successfully into its transfer orbit.

As has become almost casually expected for a launch system that has now completed its 89th consecutive success, the terminal countdown for this flight encountered no major issues, and as dawn broke over the Florida coast, weather concerns—cumulus clouds and a chance of rain—dissipated. Liftoff occurred at the opening of the four-minute launch window, at an official range time of 06:35:00.231 EDT, with release into a nominal transfer orbit happening a little more than 68 minutes later.

NAVSTAR IIR-21 is the last of eight “modernized” replenishment spacecraft to join the GPS constellation. It will replace NAVSTAR IIA-26, an aging but still active bird that has lasted nearly twice as long as its seven-year design life since its launch in July 1996 aboard Delta 237.

Despite the success, this was a deeply melancholy event for all concerned, for this was the last time the Air Force would launch a vehicle that owed its very existence to that service. The Delta II rocket was developed by McDonnell-Douglas in response to an Air Force request for proposals following the loss of Space Shuttle Challenger in 1986, as a means to clear the resulting backlog in the launch manifest. The choice of Delta II reawakened a production line which had already been shut down, and resulted in a launch vehicle that has tallied one of the greatest records of reliability in the Space Age: over 99% in 144 launches. To date, all operational GPS satellites have been lofted on Delta II rockets: 49 in all, with only one of those failing to orbit.

Now, this chapter of spaceflight history has closed. The increased size and capability of future GPS satellites mean that they have outgrown the payload capacity of Delta II, and the Department of Defense will move to its two EELV options (Delta IV and Atlas V) for GPS as well as other missions. The launch also marked the final scheduled use of SLC-17A, one of two launch pads built at Canaveral in 1956 for the Thor ballistic missile program—a missile that formed the first stage of the original Delta model.

The military’s move away from Delta II, combined with budget concerns at NASA that prevent it from putting up enough missions to maintain the system singlehandedly, have resulted in the shutdown of the launch vehicle’s production line. A total of seven flights remain on the Delta II manifest—five from the west coast launch site at Vandenberg Air Force Base, and two from Canaveral’s SLC-17B. Another five vehicles have been built by Boeing and are in storage awaiting sale. After that, barring a major sea change in the industry, the Delta era—presently more than 49 years in the making—will come to an end.

Given the mission’s “quasi-classified” status, United Launch Alliance was precluded from webcasting the launch, and the best source for on-site updates turned out to be—once again—Justin Ray’s Mission Status Center at Spaceflight Now. Official range liftoff time from SLC-2W at Vandenberg Air Force Base was 13:24:25.757 PDT.

MDA was understandably tight-lipped about specific details, including payload size, mass, and target orbit. Nevertheless, that did not prevent spaceflight expert Jonathan McDowell from speculating on its design and mass in the latest Jonathan’s Space Report, nor independent observers from locating what they believe is STSS-ATRR in a near-circular polar orbit, roughly 470 nautical miles in altitude.

Most importantly, very little has been said about its onboard sensors and their capabilities, leaving the public with only the most general description of the spacecraft’s mission: “the Space Tracking and Surveillance System (STSS) Advanced Technology Risk Reduction (ATRR) mission… is a space-based sensor component of a layered Ballistic Missile Defense System (BMDS) to detect, track, and intercept ballistic missiles.” [ULA Mission Book]

STSS-ATRR is a $400 million pathfinder for future BMDS missions, testing the technologies that—if proven viable—will be incorporated into upcoming operational satellites. Another technology demonstrator is slated to launch on a Delta II later this summer. Both missions have seen more than their share of delays and cost overruns.

An early-morning Delta II launch from Cape Canaveral on Tuesday, 24 March 2009, has successfully placed another GPS satellite into orbit. Given the flight’s official range liftoff time of 04:34:00.244 EDT, this reporter slept through the whole thing—but Spaceflight Now‘s Justin Ray was awake and filed another entry in his continuing series of excellent mission status reports.

The flight marked the 87th success in a row for the venerable Delta II, a record dating back to 1997. There now remains only one Delta II launch for the Global Positioning System, currently scheduled for late summer.

On the evening of Friday, 6 March, a three-stage Delta II 7925 launched NASA’s newest observatory, Kepler. The official liftoff time from Cape Canaveral’s SLC-17B was 03:49:57.465 UTC on 7 March. As usual, Spaceflight Now provided a complete play-by-play in its Mission Status Center.

Kepler is the first concentrated attempt at seeking out terrestrial planets—i.e., those roughly the size of Earth. It will do this by watching stars closely to spot the minute dimming caused by periodic transits of planets across the stars’ visible faces. Using Johannes Kepler’s Third Law of planetary motion scientists will be able to determine the planet’s orbit, and from there extrapolate its mass and estimated surface temperature. Thus they may figure out whether the planet might be capable of supporting life similar to that on Earth.

The next Delta II launch will be NASA’s Earth-size-planet hunter, Kepler. It is currently targeted for the late evening of 6 March EST (early morning 7 March UTC), pending a positive Flight Readiness Review today as well as confirmation of range availability by the USAF. The launch was delayed by one day to give engineers additional time to review possible hardware commonalities with the Taurus XL launch vehicle, which splashed NASA’s Orbiting Carbon Observatory last week after its payload fairing failed to separate properly.

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